It is proposed to develop a detailed understanding of the properties and behavior of retinal by synthesis of information obtained in experimental and theoretical studies of polyenes and polyene aldehydes. The techniques to be used include: conformational analysis by NMR, IR and Raman spectroscopy, location of excited state energy levels by UV, CD and MCD spectroscopy, determination of the lifetimes of states and of the dynamics of cis-trans isomerization by nanosecond and picosecond pulsed time resolved fluorescence spectroscopy, and the development of theoretical models of the static and dynamic properties of the model molecules and retinal. Experiments will at first be limited to isolated molecules (gas phase) and later extended to condensed media.